Method of treating photographic paper.



EDWARD ALBERT CUNNINGHAM, OF AMBRIDGE, PENNSYLVANIA.

METHOD or TREATING rnoroennrmc PAPER.

Specification of LettersPatent.

meanin 11, 1908.

Application filed April 9, 1908. Serial No. 426,001.

' T 0 all whom 'itmay concern:

Be it known that I, EDWARD ALBEl-t'l CUN- NINGHAM, of Ambridge, in thecounty of Beaver and State of Pennsylvania, have inventeda new anduseful Method of Treating Photographic Paper, of which the following isa specification.

My invention relates to photographic paper and has for'its object theeconomical treatment of photographic paper, so that prints of anysuitable color may be made,

and other prints made from those first treated. i

'A further object to providea cheap and efficient photographic paperwhich will be unaffected by sunlight and other climatic conditions. I gV My invention isspecially adapted for the treatment of the paper usedin what is known as the blue printing process, since by its applicationI am able to change the actinic blue color of the prints to anon-actinic color,

In carrying out my invention I treat the prints, after being washed,with a solution or solutions ofasalt of one or more of the elements,preferably of the double salts of cop per and potassium chlorid, therebycoating those portions of the prints which have been acted on by light.The print is-then washed and transferred to a solution or solutions ofat least one of the sulfide or thio-sulfates. preferably the sulfid ofsodium, which changes the coating obtained by the first treatment into asulfid of the element or elements used. The print is then washed ordried in the usual manner. If the double salts of copper are used in thecoating treatmeni, then, whcnthc print is subsequently treatedby thesulfide or thi osulfates, the double salts of copper will accordingly bechanged into sulfids ofcoppe l? Those skilled. 'I'nthe art may vary' themethod of treatment described above without departing from the scope andspirit of my invention, since i.

What I claim is:

1. The herein described method of treat ing photographic paper, whichconsists in placing a photographic print in a solution containing saltsof one of the metals, whereby said print 'is coated With-said saltsfandthen treating said print with a solution which will change the depositedmetal into a v sulfid.

ing photographic paper, which consists in placing a photographic printin a solution containing a salt of copper, whereby saidprint is coatedwith said-sc opper andtransferring said print into a solution which willchange the deposited copper into a sulfid.

3. The hereln described method of treating photographic paper, whichconsists in placing a photographic print in a solution containing doublesalts of copper and potassium chlorid whereby the print is coated withsaid salt, and then subjecting said print to a solution which willchange the deposited copper into a sulfid of copper.

4. The herein described method of treat- 2. The herein describediriethod of treat-- ing photographic paper, which consist in placing aphotographic print in a soiulion containing a salt of one of the metals,where by said print is coated with said salts, and transferring saidprint into a solution containing a salt of sodium, wherebythe salt ofthe metal is changed into a sulfid.

5. The herein described method of treating photographic paper, whichconsists in placing a photographic print in a solution containing a saltof one of the'metals, whereby said print is coated with said salt,washing said print, and inserting said print into a second solutioncontaining a sulfid, whereby said sulfid acts on the coating on saidprint to change said salt in said coating into sulfid, and then Washingand drying the print.

6. The herein described method of treat- Q ing photographic paper, whichconsists in immersing a photographic print ina solution containing thedouble salts of copper and po.

